Just a short little tutorial on how to add your Movies and your iTunes music (from both your local and network machines). This tutorial is using Plex 0.7.5. The seven series of plex is considered a beta right now but there are some exciting additions such as the Plex Media Center (which is currently the best way to integrate iTunes into your music center besides using Front Row or the Apple TV). http://plexapp.com
More specific info can be found on the wiki.
Adding Media to Library:
Plex Media Server for iTunes integration: